Not applicable.
In industrial processes in which complex assemblies are made from a variety of small parts, whether made on site or packaged and shipped from elsewhere, parts washers are commonly used to wash individual parts so that they are free of dirt and oil and will fit smoothly in the assembly process. Generally, these parts washers fall into one of two categories, batch-type washers or continuous flow washers. Batch-type washers require parts to be washed batch-by-batch, while continuous washers allow for a continuous flow of parts through a washing apparatus without disrupting the flow of an assembly line,
Most parts washers operate using aqueous solutions or solvent based cleaning strategies. Typical cleaning strategies depend upon the interaction of three factors: heat, force and chemistry. In the case of aqueous Cleaning technology, force is the dominant factor, while chemistry and heat play supporting roles. In aqueous cleaning processes, chemical detergents are applied to penetrate the dirt or oil found on the surface of a part, in order to wet the underlying part surface. Heat, on the other hand, is used to speed up the rate to which chemical detergents react with or penetrate the dirt or oil, while, at the same time, thinning out the dirt or oil by reducing its viscosity. An ample amount of force is then applied to effectively wash the oil or dirt from the part""s surface. In the absence of chemical detergents or heat, a substantial force is necessary to break the oil or dirt away from a part""s surface. Often times, this results in ineffective cleaning or the consumption of substantial amounts of energy. On the other hand, the use of chemical detergents results in dirt or oil being more easily removed with less force being necessary. Unfortunately, these chemical detergents are often expensive and toxic to nature. In today""s industry, most, if not all, continuous flow-type parts washers are based on the use of detergents or other solvents.
The force applied in aqueous cleaning strategies may be by either a high pressure spray or ultrasonic energy. In prior art ultrasonic cleaning systems, ultrasonic transducers produced ultrasonic pressure waves which, when coupled to a liquid medium, causes dirt and oil to be dislodged from parts bathed in an aqueous solution. In order to be effective, however, typically this requires either a significant force or an aqueous solution of chemical detergents and heat as described above.
One ultrasonic washer in use today places manufacture parts to be cleaned in baskets which are moved through an ultrasonic field (U.S. Pat. No. 2,845,077). A disadvantage of this method is that parts which are located in the shadow of other parts in the ultrasonic field receive significantly weaker exposure to ultrasonic energy than those which are directly exposed to the ultrasonic energy. Other ultrasonic washers have attempted to solve this problem by introducing various ultrasonic continuous flow-type washing methods and devices which are intended to enhance the exposure of the manufacture parts to the ultrasonic field. One washer includes a tank where parts sink vertically against the upward flow of a cleaning solution to a bottom where an auger drives the parts up out of the solution and into a collection hopper (U.S. Pat. No. 2,973,312). Another washer utilizes a vibratory surface, placed within a cleaning solution, which serves as a conveyor belt to move parts through the cleaning solution and as a means of creating ultrasonic energy (U.S. Pat. No. 4,194,922). A third apparatus moves bearings through an ultrasonic force by a stationary conveyor mechanism housed in a reservoir containing a cleaning solution where the force cleans and moves the bearings along (U.S. Pat. No. 4,057,070).
In all these cases, the ultrasonic force is generated from outside of the reservoir containing the parts and the aqueous cleaning solution. Because of this, the ultrasonic energy must pass through a coupling medium, usually water, and/or the walls enclosing the cleaning reservoir before it can couple with the aqueous cleaning solution, usually containing a chemical detergent, and effectively clean the manufactured parts. The distance this energy must travel and the several elements it must travel through, in turn, decreases the strength of the ultrasonic force available to effectively clean the manufacture parts. In order to rectify this problem, either a substantial chemical detergent, a significant amount of heat, or a strong ultrasonic energy wave generated by relatively high energy transducers must be employed to achieve the desired degree of cleaning. Of course, this will result in substantial cost and inefficiencies, including the additional expense of purchasing and disposing of cleaning detergents and the increased cost of electricity for generating heat or ultrasonic energy.
The method and apparatus of the present invention is summarized in that a novel method for cleaning manufacture parts using an ultrasonic continuous flow-type process is disclosed. The present invention is further summarized in that it provides for a method of washing small manufacture parts in an apparatus requiring small volumes of water, no cleaning solutions, and an ultrasonic transducer system wherein the ratio of ultrasonic power per volume of water is at a level well above that for other ultrasonic washers in use today.
More specifically, disclosed is a method and apparatus comprising washing small manufacture parts in an apparatus requiring no cleaning solutions, wherein soiled parts are segregated and passed singly along through a feeding mechanism, and into a cleaning station such that the parts are immersed in a small volume of hot water and passed through an ultrasonic field generated by one or more ultrasonic transducers placed in close proximity to the moving parts and located within the small volume of water, until they are passed up another tapered collar and out of the hot water where they travel through a rinsing station and a drying station. The feeding mechanism then moves the parts out of the ultrasonic washer and onto other applications.
It is an object of the present invention to provide an ultrasonic continuous flow-type parts washer which uses a small volume of water, no cleaning solutions, and an efficient ultrasonic transducer system where the ratio of ultrasonic power per volume of water is at a level well above that for other ultrasonic washers in use today.
It is another object of the present invention to provide a feeding mechanism for a continuous flow-type parts washer that allows the introduction of soiled manufacture parts into an aqueous solution so that ultrasonic energy can be coupled through the solution, while still moving the parts out again and onto further applications.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference must be made therefore to the claims herein for interpreting the scope of the invention.